Saturday, August 30, 2014

1528. On the Human Caused Sixth Great Mass Extinction: Have We Learned Anything from the Case of the Passenger Pigeon?

Passenger pigeon was probably the most abundant bird species ever lived until it went extinct hundred years ago this week when the last of them called Martha died in Cincinnati Zoo

ITHACA, N.Y. — THE passenger pigeon is among the most famous of American birds, but not because of its beauty, or its 60-mile-an-hour flight speed. Nor is it a cherished symbol of our great country. No, we remember the passenger pigeon because of the largest-scale human-caused extinction in history.

Possibly the most abundant bird ever to have existed, this gregarious pigeon once migrated in giant flocks that sometimes exceeded three billion, darkening the skies over eastern North America for days at a time. No wild bird in the world comes close to those numbers today. Yet 100 years ago this week, the very last pigeon of her kind died in her cage at the Cincinnati Zoo. Her name was Martha, and her passing merits our close attention today.

Mercilessly slaughtered by the tens of millions at breeding colonies in the North and at huge wintertime roosts in the South during the post-Civil War era, passenger pigeons were shipped by trainloads to dinner tables in homes and restaurants across the East. Their population fell from biblical numbers at midcentury to tiny, aimless flocks in 1890. By around 1900 the few birds that remained were all in captivity. The last male died in 1910, leaving Martha as a barren relic of past abundance.

Martha is receiving plenty of eulogies this year, including several recent books and even a petition for a presidential proclamation honoring her centenary. I suggest that our most important eulogy would be to reflect on her species’ once great numbers, on the century that has passed since her death and on the century that begins today. We need to imagine Martha asking us, “Have you learned anything from my passing?”

It seems that whenever humans discover bounty, it is doomed to become a fleeting resource. The fate of cod fisheries in the late 1900s mirrors that of the passenger pigeon a century before. Pacific bluefin tuna, down 96 percent from their unfished numbers, may be next in line. Countless such examples exist around the world, but the good news is that we still have time to reflect on them before their populations dwindle down to their last respective Marthas.

This is the message of the 2014 State of the Birds report, a periodic assessment of the health of our nation’s bird populations compiled by the nation’s leading bird conservation specialists in collaboration with state and federal wildlife agencies.

The report, which is to be released Sept. 9, uses data from long-running, continentwide population surveys to analyze which bird communities are doing well, and which are in trouble. The results show some clear lessons that — had we followed them in the late 1800s — could have saved the passenger pigeon.

Perhaps the most significant conclusion is a simple validation: Timely conservation action really does work, even for species that have reached alarmingly low numbers. But let’s emphasize that word “timely.” After all, several states did pass laws to restrict pigeon hunting, but they did so after passenger pigeons were reduced to a few stray flocks. For a species that laid only a single egg in the nest, and may have required the social stimulus of large flocks to breed, these meager actions were too little, too late.

Unlike the Americans of the 1800s, today we have an arsenal of gauges that allows us to measure how bird species are faring. The Audubon Christmas Bird Count, the Breeding Bird Survey by the United States Geological Survey and Canadian Wildlife Service, and the Cornell Lab of Ornithology’s eBird data-collection program provide robust continentwide estimates of population sizes and trends. Because birds are such sensitive barometers of landscape health, these measures help us identify deeper environmental issues that demand attention. Peregrine falcons and bald eagles, for example, demonstrated that our underregulated pesticide habits were poisoning the environment, and us. But once we knew this, we acted decisively — and it worked. Both of these species are now off the endangered species list, and our environment is vastly healthier than when these species were declining precipitously.

The Endangered Species Act is by far the most powerful piece of environmental legislation ever passed. Today, the act continues to be a source of on-the-ground success — a steadfast reminder that timely conservation pays off. Thanks to the emergency actions authorized and funded by the act beginning in the 1980s, just a few weeks ago I saw two majestic California condors flying free in the federally protected Ventana Wilderness near Big Sur. There is scarcely a sight in the natural world more thrilling, and the emerging success of the condor breeding and reintroduction program should be a source of immense national pride. Still, the condor’s susceptibility to lead poisoning, mainly from hunters’ bullets, reminds us that much remains to be done to secure its future.

The State of the Birds report documents that for every success story, a number of other birds and their habitats are in serious danger. The report cites 230 species on a watch list of birds that are currently in danger of extinction or at risk of becoming so without significant conservation action.

With dozens of species on the list, Hawaii leads all regions in the United States in terms of threats, yet receives less than 5 percent of the recovery funding from the federal government’s endangered species program. Presumably this is because more charismatic species receive a disproportionate share.

The list also highlights the plights of seabirds, like albatrosses and petrels; shorebirds, like plovers and sandpipers; and four high-profile species of grouse, which perform spectacular spring mating dances in 18 states across our prairies and Western sagebrush.

These days the Endangered Species Act seems to be considered by many to be a hostile government action, as evidenced most recently by intense political responses, including efforts in Congress to block adding the sage grouse to the endangered species list, and to weaken key provisions of the act. Yet, on this centenary of Martha’s death, it bears reflection that a strong federal Endangered Species Act would have saved the passenger pigeon a century and a half ago.

Preserving abundance in nature is ecologically just as important as rescuing rare species en route to extinction. The passenger pigeon taught us that even the most numerous species can undergo population collapses in astonishingly short periods of time. Cod fishermen of the North Atlantic learned the same painful lesson just two decades ago. It is far more effective and cost-efficient to conserve a species while it is abundant than to wait until it reaches the brink.

The State of the Birds report identifies more than two dozen “common birds in steep decline” — species that are showing early warning signals of distress, having recently lost more than half of their global populations. Mostly, these species are barometers for greater environmental issues. The eastern meadowlark and northern bobwhite are fading from rural America right along with the family farm and its smaller-scale agricultural practices of pasturing cows and keeping grass buffers. Common nighthawks, those fantastic evening acrobats that flash through our ball-field lights to catch bugs on summer nights, are disappearing alongside native pollinators like bees. Many experts suspect that continent-scale declines in the prey of insect-eating birds have resulted from agricultural and homeowner insecticide use.

I suggest that the broader conservation argument transcends cost efficiencies and scientific analyses and should focus instead on the moral questions posed by Martha. Most of us wish we could see those storied passenger pigeon flocks for ourselves, so why aren’t we doing everything possible to keep some of our most common wild things from meeting the same fate? Don’t our great-grandchildren have the right, as part of their American heritage, to experience choruses of meadowlarks singing “spring is here!” from treetops and fence posts?

In the past century, we have built the greatest conservation system in the world. Sadly, the passenger pigeon just missed the dawn of conservation in America. In 1900 the Lacey Act became our nation’s first federal wildlife protection law, and three years later President Theodore Roosevelt saved pelicans and egrets from plume hunters by establishing Pelican Island in Florida as our first national wildlife refuge. Numerous other laws and actions followed, including the Migratory Bird Treaty Act of 1918, which still protects all nongame birds today.

A century after Martha’s death, the results of bold conservation actions are all around us, and are not limited to high-profile birds like falcons and eagles. The State of the Birds report shows that wetland birds altogether have increased significantly since 1968. The reason for this growth of waterfowl populations like the mallard, blue-winged teal and gadwall dates from the 1930s, when federal laws established the Migratory Bird Hunting and Conservation Stamp Act and an excise tax on firearms and ammunition to provide funding for wildlife management and habitat protection.

The report’s population indicators also identify habitats where conservation investments are desperately needed today. “Aridland” birds of the American desert, chaparral and sagebrush — such as the sage grouse, gilded flicker and black-throated sparrow — have declined by nearly half since 1968. These declines, driven primarily by habitat loss and fragmentation owing to energy and residential development, have been exacerbated recently by severe drought. Drive along our iconic Western desert highways and you may not notice anything unusual, but it’s a bird habitat in crisis.

Why should we care about these aridland birds, or any birds? It’s a common question, as elected officials and voters weigh conservation investments alongside health care, immigration and economic issues.

Besides our moral imperative to maintain the earth’s beauty and bounty for future generations to enjoy, it is important to view birds as accessible indicators of the health of our lands and waters. Take those declining meadowlarks as one example: In my home state of Minnesota, where meadowlarks commonly sang atop utility poles back in the 1950s, the patches of wild grasslands they depended on are now horizon-to-horizon farm fields. As a consequence, barges now get stuck in sediment-filled portions of the Mississippi River because grasslands no longer intercept silt-laden runoff waters from farms. The toxic algae bloom in Lake Erie that recently rendered Toledo’s water supply undrinkable had a similar origin. In short, healthy bird habitat makes for healthy human habitat.

If the image of train cars filled with passenger pigeons stuffed 300 to the barrel stands as our most infamous icon of carelessly unsustainable exploitation, then we need to return to the Martha question: “Have you learned anything from my passing?” As we plunder the final few percent of our once abundant ocean fisheries, perhaps we should start referring to bluefin tuna as passenger pigeons of the sea.

Roosevelt’s pelicans and egrets recovered because our nation made their continued abundance a priority and took bold action. But with 230 species on the 2014 State of the Birds watch list, the job Roosevelt pioneered is not at all finished. Like good housekeeping, or maintaining a strong military, conservation is not a one-and-done proposition. It requires continued commitment and investment.

Naysayers wrongly told Roosevelt that seeking to restore and maintain nature’s plenty wasn’t financially practicable, that it would disrupt economic growth. He did not heed these dire warnings, and instead championed actions that would avoid repeating the passenger pigeon mistake.

Today, the tragedy of the passenger pigeon exhorts us to have the courage to redouble these efforts in protecting what remains of nature’s abundance.